[Composer] Bump guzzlehttp/guzzle to version 7 to suppress deprecation notices

- Bump divineomega/password_exposed to version 3 to remove dependency on Guzzle version 6
- Add new ICanHandleHttpResponses->getBodyString method to solve inheritance mismatch with GuzzleHttp\Psr7\ResponseInterface->getBody return type

src/Network/HTTPClient/Response/GuzzleResponse.php

@@ -163,8 +163,7 @@ class GuzzleResponse extends Response implements ICanHandleHttpResponses, Respon
 		return $this->isTimeout;
 	}
 
-	/// @todo - fix mismatching use of "getBody()" as string here and parent "getBody()" as streaminterface
-	public function getBody(): string
+	public function getBodyString(): string
 	{
 		return (string) parent::getBody();
 	}